Our results suggest that rates of PDD are higher than previously reported. Methodological limitations in existing epidemiological investigations preclude interpretation of recent high rates as indicative of increased incidence of these disorders although this hypothesis requires further rigorous testing. Attention is nevertheless drawn to the important needs of a substantial minority of preschool children.

The rate of pervasive developmental disorders is higher than reported 15 years ago. The rate in this study is comparable to that in previous birth cohorts from the same area and surveyed with the same methods, suggesting a stable incidence.

ABSTRACT. Objective. A link has been postulated between measles-mumps-rubella (MMR) vaccine and a form of autism that is a combination of developmental regression and gastrointestinal symptoms that occur shortly after immunization. This hypothesis has involved 3 separate claims: 1) that there is new phenotype of autism involving regression and gastrointestinal symptoms, 2) that this new variant is responsible for the alleged rise of autism rates, and 3) that this phenotype is associated with biological findings suggestive of the persistence of measles infection. We tested the first of these claims. If this new "autistic enterocolitis" syndrome had some validity, then 1 or several of the following 6 predictions should be supported by empirical data: 1) childhood disintegrative disorder has become more frequent, 2) the mean age of first parental concern for autistic children who are exposed to MMR is closer to the mean immunization age than in children who are not exposed to MMR, 3) regression in the development of children with autism has become more common in MMR-vaccinated children, 4) the age of onset for autistic children with regression clusters around the MMR immunization date and is different from that of autistic children without regression, 5) children with regressive autism have distinct symptom and severity profiles, and 6) regressive autism is associated with gastrointestinal symptoms and/or inflammatory bowel disorder.Methods. Three samples were used. Epidemiologic data on 96 children (95 immunized with MMR at a median age of 13.5 months) who were born between 1992 and 1995 and had a pervasive developmental disorder diagnosis as reported in a recent UK survey (post-MMR sample) were compared with data from 2 previous clinical samples (1 pre-MMR [n ‫؍‬ 98] and 1 post-MMR [n ‫؍‬ 68]) of autistic patients. All patients were assessed with the standardized Autism Diagnostic Interview (ADI), allowing rigorous comparison of age at first parental concerns and rates of regression across samples. Reliability was excellent on ADI scores, age of parental concern, and developmental regression. Furthermore, data on bowel symptoms and disorders were available in the epidemiologic survey from both pediatric and parental sources, and immunization dates were obtained from computerized records.Results. The prevalence of childhood disintegrative disorder was 0.6/10 000 (95% confidence interval: 0.02-3.6/10 000); this very low rate is consistent with previous estimates and is not suggestive of an increased frequency of this form of pervasive developmental disorder in samples of children who are immunized with MMR. There was no difference in the mean age at first parental concern between the 2 samples exposed to MMR (19.3 and 19.2 months) and the pre-MMR sample (19.5 months). Thus, MMR immunization was not associated with a shift toward an earlier age for first parental concerns. Similarly, the rate of developmental regression reported in the post-MMR sample (15.6%) was not different from that in the pre-MMR sample (18.4%)...

This study aimed to determine if relatives of children with autism and less severe pervasive developmental disorders (PDDs) have higher rates of various components of the broad autistic phenotype. Psychiatric and medical disorders were investigated. Parents of children with PDDs were selected from an epidemiological survey and compared with parents of control children with non-autistic developmental problems. Rates of abnormalities and disorders were compared in relatives of 79 cases and 61 controls. Medical and autoimmune disorders in both groups were endorsed by few relatives. Specific developmental disorders were commoner in parents of controls. Depression and anxiety were significantly more prevalent in mothers of children with PDDs. Significantly more PDD children had at least one first-degree relative with anxiety and one second-degree relative with OCD. PDDs were commoner in first-degree relatives. The implications of the findings for the definition of the broad phenotype of autism are discussed.

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